The need to resort to an automatic transfer between successive work stations has already been felt for a long time, in order to rationalize a process of manufacture, of assembly, of mounting or of treatment and to reduce, if not eliminate, human intervention at each operational phase of such a process.
To attain this object, the prior art has proposed several solutions which may be classified in two families corresponding, respectively, to transfer machines with bound carriages and to transfer machines with free carriages.
The present invention concerns the transfer machines with free carriages and, more particularly, to those comprising independent and motorized free carriages.
Such transfer machines have incontestably brought considerable improvements, particularly by offering a possibility of modulating the speed of displacement of each carriage between the work stations.
The implantation of such machines and starting up thereof have, however, shown that, despite the undeniable advantages that they bring, they are still penalized by the absence of suppleness offered by their configuration in the possibility of adaptation of the circulation circuit that they define for the carriages.
Now, the economical imperatives of use of such transfer machines, of a high cost price, involve their being able to offer an adaptation of the configuration of the trackway for circulation of the carriages in order to ensure therefor a flexibility of use for the development of monitoring, assembly, mounting, testing processes capable of knowing phases of development which vary depending on the requirements of intervention on the loads or workpieces borne by the carriages and transferred by the latter from station to station.
Furthermore, a transfer machine presenting at least one rectilinear trackway for circulation, frequently requires the implantation of by-passes to bring the carriages opposite work stations excluded from the line of orientation, when, for example, their time of operation is greater than the longest having been taken as base for determining the overall operational cycle.
In such a case, it is therefore necessary to provide an outlet by-pass, a trackway for orientation up to the station and a return by-pass for the carriage to be able to reintegrate the principal circulation trackway.
In implantations of more or less complex type, by-passes are also frequently encountered for contiguous stations with, therefore, the same requirements.
In such a case, it is necessary to provide for two contiguous derivative stations and for each of them, an inlet by-pass, a transfer branch and an outlet by-pass.
The installation therefore employs contiguous by-passes with specific functions which considerably increase the implantation and bulk.
In addition to the above configuration, it would also be desirable, in transfer machines with more or less complex circulation circuit, i.e. initially designed to offer a considerable flexibility of adaptation, to be able to have a module able to ensure communication between two circulation trackways of privileged or principal character.
Such a possibility would enable carriages to be transferred from one trackway to the other in accordance with the program of circulation to be followed temporarily with the same installation capable of being employed for different programs.